Median Nerve Injury: Index Finger Flexion Sign
The inability to flex the index finger is a specific clinical sign often associated with damage to the median nerve.
Role of the Median Nerve
The median nerve controls several muscles in the forearm and hand. Specifically, it innervates the flexor digitorum superficialis (FDS) muscle, which is a primary flexor of the finger at the proximal interphalangeal (PIP) joint. It also contributes to the flexion of the index finger at the metacarpophalangeal (MCP) joint via the first lumbrical muscle.
- Injury to the median nerve can impair the function of the FDS muscle.
- This impairment leads to difficulty or inability in flexing the index finger, particularly noticeable at the PIP joint.
Evaluating Other Options
The other options are less likely to cause this specific symptom:
- Ulnar nerve injury: Primarily affects the little and ring fingers, and hand intrinsic muscles responsible for abduction, adduction, and thumb opposition.
- Radial nerve injury: Affects wrist and finger extension (causing wrist drop) and sensation on the back of the hand. It does not directly impact finger flexion.
- Dupuytren's contracture: A condition causing thickening of the palmar fascia, leading to finger flexion contractures (usually ring and little fingers), but not an *inability* to actively flex due to nerve damage.
Conclusion
Therefore, the inability to flex the index finger strongly suggests a lesion affecting the median nerve.
Important Questions from Bones & Joints
- A 40-year-old lady complains of progressive deformities of her hands and fingers associated with stiffness which is present in both the hands and improves as the day progresses. On examination, there is symmetrical involvement of hands and fingers of both the upper limbs with flexion and ulnar deviation at the metacarpophalangeal joints. What is the most likely diagnosis in this lady?
- A 52-year-old female complains of increasing pain in the right shoulder. She is also finding it increasingly difficult to do overhead abduction of the affected joint. She had been diagnosed as a diabetic 20 years back and is on treatment since then. What is the most likely cause of her clinical condition?
Consider the following :
1. Pain relief
2. Prevention of infection
3. Anaesthesia
4. Restoration of anatomy
Which of the features given above are benefits of fracture treatment?
- Hangman's fracture is
- Which of the following is NOT true about Dupuytren's Contracture?
